The Void is the place where there is nothing. It is not emptiness in the sense of lack, but in the sense of infinite potential. When you are in the Void, you have no technique, yet you can execute all techniques.
The mind must be like water. Calm and reflective. If the mind is agitated, it cannot reflect the opponent's intentions. When the mind stops at a thought (fear, anger, pride), the flow is broken, and you die.
Do not look at the opponent's sword; look at his spirit. Perception is strong and sight is weak. In strategy, it is important to see distant things as if they were close, and to take a distanced view of close things.